This site give u full details of building a linux distribution of your own. The famous distributions available usually occupy lots of ur valuable disk space and wasting them . Now you can build a complete linux distribution which is less than 100 MB. There are certain areas like embedded systems where there is need for a small OS. It is possible to have a linux which is just 5 MB in size after stripping all those unnecessary parts of the OS. Have fun creating ur own linux distro ....